The great guys at NASA just observed the largest Gamma Ray Burst in recorded history. Luckily, it was far enough away not to cook us:
Astronomers believe most occur when exotic massive stars run out of nuclear fuel. As a star's core collapses into a black hole, jets of material — powered by processes not yet fully understood — blast outward at nearly the speed of light. The jets bore all the way through the collapsing star and continue into space, where they interact with gas previously shed by the star and generate bright afterglows that fade with time. ...Fermi team members calculated that the blast exceeded the power of approximately 9,000 ordinary supernovae, if the energy was emitted equally in all directions.
That's a biggun. I hope I was on the other side of our planet at the time.